If you want to hate on Harbaugh that's OK but blaming it on his 4th down decisions is ass and reactionary because you wouldn't be saying that had they converted.
Ravens were doing this all year, led the league in 4th down conversion rate and 4th downs converted. They also converted every 4th and 1 in the regular season. Obviously it's dangerous because if it backfires, you could surrender field position/points...but on average they were converting enough of them to make up for that risk.
You could argue that Harbaugh should have been more conservative and not done shyt like that, but playing conservative isn't a magic recipe to win in the playoffs either.